JP6203050B2 - Liquid fermented milk and method for producing the same - Google Patents

Description

  The present invention relates to liquid fermented milk and a method for producing the same.

In recent years, there has been a demand for a fermented milk with a mild taste and a mild taste, among consumers' genuine and mild intentions.
As an example of a method for producing fermented milk having a weak acidity, a fermented milk mix in which the ratio of non-fat milk solids to milk fat is 2 to 6 by weight is stored at 10 ° C. for 14 days. A liquid fermented milk characterized by cultivating a curd so as to have a pH of 4.9 to 5.3 at the end of fermentation using a lactic acid bacterium having a pH decrease of less than 0.3. A manufacturing method has been proposed (Patent Document 1).
As another example of a method for producing fermented milk having a weak acidity, when producing a fermented milk food or drink containing a Bifidobacterium bacterium having a product pH of 5.4 or more, the fermentation of the raw milk is at least bifidobacteria. Bifidobacterium genus characterized in that it is performed with one or more lactic acid bacteria or bifidobacteria belonging to the bifidum, and an alkali salt is added to the food or drink at any stage after the fermentation step. A method for producing bacteria-containing fermented milk food and drink has been proposed (Patent Document 2).

JP-A-6-14706 JP 2002-204655 A

According to the production method described in Patent Document 1 described above, the storage stability is good even at around pH 5.0, there is little water separation / precipitation without using a stabilizer such as pectin, and the stabilizer such as pectin. Because no paste is used, there is no pasty feeling and the texture is good. Furthermore, since the pH is higher than usual, it is possible to produce a liquid fermented milk with a low acidity and a mild mouthfeel.
However, when the present inventor examined the manufacturing conditions of the manufacturing method described in Patent Document 1, when preparing a card of fermented milk mix so that the pH at the end of fermentation exceeds 5.3, the liquid of the card During storage as liquid fermented milk that is the final product after conversion (in other words, homogenization treatment), precipitates are formed due to aggregation of components in the liquid fermented milk, and the appearance and texture may deteriorate. I got the knowledge.
An object of the present invention is to provide a liquid fermented milk having a weak acidity, a mild taste, and a precipitate that does not form during storage and does not deteriorate in appearance, flavor and texture, and a method for producing the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the pH of the curd after the completion of fermentation is 5.0 to 6.0 higher than usual, but 30 higher than the conventional 10 to 15 MPa. When homogenization treatment is performed under a pressure of ˜100 MPa, liquid fermented milk having a weak acidity and mild taste can be obtained, and no precipitate is generated during storage of the liquid fermented milk. However, the present inventors have found that the amount is very small and completed the present invention.

That is, the present invention provides the following [1] to [6].
[1] (A) A card preparation step in which a lactic acid bacterium is added to a raw material of fermented milk and fermented to prepare a card having a pH of 5.0 to 6.0, and (B) the above card is homogeneous under a pressure of 30 to 100 MPa. A process for producing liquid fermented milk having a pH of 5.0 or more, comprising a homogenization treatment step for obtaining a liquid fermented milk having a pH of 5.0 to 6.0.
[2] Liquid fermented milk obtained by the method for producing liquid fermented milk according to [1].
[3] The liquid fermented milk according to [2], wherein the viscosity is 10 mPa · s or less.
[4] The liquid fermented milk according to [2] or [3], wherein the acidity is 1.0% or less.
[5] The liquid fermented milk according to [2] or [3], wherein the acidity is 0.5% or less.
[6] The liquid fermented milk according to any one of [2] to [5], which does not contain a thickening stabilizer.

The liquid fermented milk of the present invention is subjected to a homogenization treatment under a specific pressure, and since the pH after the homogenization treatment is 5.0 to 6.0, the acidity is weak and a mild (mellow) mouthfeel, It can be maintained between pH 5.0 and above. In addition, since the acidity is weak, the amount of sugar and other sweeteners that need to be added when the acidity is strong can be reduced to zero or a small amount, which matches the preference of health-conscious consumers.
Moreover, since the liquid fermented milk of this invention is performing the homogenization process under the pressure of 30-100 Mpa, isolation | separation and coagulation | solidification of a component do not generate | occur | produce over a long storage period, but a precipitate (solid content) The appearance, flavor and texture of the liquid fermented milk can be maintained.
In addition, the liquid fermented milk of the present invention does not require the addition of a thickening stabilizer such as pectin or carboxymethylcellulose (CMC) in order to suppress the formation of precipitates during storage, and is a good throat with no pasty feeling. You can give it over. In this case, the liquid fermented milk of the present invention also meets the tastes of genuine consumers who are not added.
Furthermore, the liquid fermented milk of the present invention can be easily produced with the same number of steps and production time as conventional.

  The method for producing liquid fermented milk having a pH of 5.0 or more according to the present invention comprises: (A) a card preparation step of adding a lactic acid bacterium to a fermented milk raw material and fermenting to prepare a card having a pH of 5.0 to 6.0; B) The homogenization process of the said card | curd is performed under the pressure of 30-100 Mpa, and the liquid fermented milk of pH 5.0-6.0 is obtained. Hereinafter, each process will be described in detail.

[Step (A); card preparation step]
Step (A) is a step of preparing a curd having a pH of 5.0 to 6.0 by adding lactic acid bacteria to the raw material of fermented milk and fermenting it.
In this specification, the raw material of fermented milk means what contains at least raw material milk.
Examples of raw milk include animal milk such as cow's milk, processed products thereof (for example, skim milk, skim milk powder, spinach milk, whey, cream, etc.), vegetable milk such as soybean milk derived from soybeans, etc. Is mentioned.
As an example of the raw material of fermented milk, what is called fermented milk raw material mix is mentioned.
A fermented milk raw material mix is a mixture containing raw material milk and other ingredients, for example, raw materials commonly used in the production of fermented milk, such as raw milk, sugar, sugars other than sugar, high-sensitivity sweeteners, flavorings, water, etc. Can be obtained by heating and dissolving and mixing.
In addition, the composition of raw milk and processed milk products such as milk fat and non-fat milk solids (milk protein, lactose, ash) varies depending on individual animals, breeding environment, climate, etc., and is actually used. It goes without saying that raw milk and processed milk products can be selected according to the composition of the raw material and an appropriate blending ratio can be set each time.
The raw material of fermented milk (for example, animal milk such as cow milk) can be preliminarily heated and sterilized. In this case, examples of the sterilization method include UHT (ultra high temperature sterilization) that sterilizes at 120 to 130 ° C. for several seconds, HTST (high temperature sterilization) that sterilizes at 90 to 95 ° C. for several tens of minutes, and the like.

Lactic acid bacteria are not particularly limited as long as they are strains used in fermented milk such as yogurt. The strain is not limited to the verification contents of the examples described below, and in particular, if a lactic acid bacterium having a small increase in acidity during refrigerated storage is appropriately selected and used, the storage period of the liquid fermented milk can be extended. For example, when liquid fermented milk is prepared by the production method of the present invention and it takes 15 days to reach pH 5.0 during refrigerated storage, the storage period of 15 days (period that can be consumed as the liquid fermented milk of the present invention) ) Can be set. Moreover, when liquid fermented milk is prepared with the manufacturing method of the present invention and it takes 30 days to reach pH 5.0 during refrigerated storage, a storage period of 30 days can be set. That is, the smaller the increase in acidity and / or pH decrease of the liquid fermented milk of the present invention during refrigerated storage, the longer the effect of the present invention can be enjoyed after production.
Moreover, the time of the storage start of liquid fermented milk here is the time of adjusting the liquid temperature of liquid fermented milk to storage temperature (for example, 10 degreeC) after completion | finish of homogenization processing (storage temperature is 10 degreeC, and When the homogenization process is performed at 10 ° C., the homogenization process is completed).

  Whether or not the strain of lactic acid bacteria can be used in the present invention may be affected by the component composition of liquid fermented milk. For example, when using a raw material for fermented milk having a component composition that does not easily lower the pH, the condition of “the pH of fermented milk during cold storage is 5.0 or more” is easily satisfied. The number of types of strains of lactic acid bacteria that can be used in is increased.

Fermentation temperature is 30-48 degreeC from a viewpoint of obtaining the fermented milk of favorable flavor efficiently, Preferably it is 35-48 degreeC, More preferably, it is 38-45 degreeC.
Fermentation time is preferably 0.5 to 10 hours, more preferably when Lactobacillus bulgaricus and Streptococcus thermophilus are used, for example, from the viewpoint of obtaining fermented milk having a pH described below and having a good flavor. Is 1 to 8 hours, more preferably 1 to 5 hours, and particularly preferably 1 to 3 hours.
The raw material of fermented milk solidifies into a card (solid form) as fermentation progresses.
The pH of the curd at the end of the fermentation is 5.0 to 6.0, preferably 5.2 to 6.0, more preferably 5.3 to 5.9, and particularly preferably 5.4 to 5.9. is there. If the pH is less than 5.0, the acidity of the liquid fermented milk may become strong during storage. When the pH exceeds 6.0, it is difficult to obtain a fermented milk having a good flavor, and the protein may aggregate during storage of the liquid fermented milk to cause a precipitate.
After completion of fermentation, the temperature of the card can be lowered to the temperature at the time of the homogenization treatment described later, or the temperature of the card can be lowered for the homogenization treatment in the subsequent step (B). In addition, the temperature of the liquid fermented milk after the homogenization treatment can be lowered to a storage temperature (for example, 10 ° C.). Thus, the time of temperature decrease is not particularly limited.

[Step (B): Homogenization treatment step]
A process (B) is a process of performing the homogenization process of the card | curd obtained at the process (A) under the pressure of 30-100 Mpa, and obtaining liquid fermented milk of pH 5.0-6.0.
The homogenization treatment can be performed by using a homogenizer (homogenizer).
The pressure of the homogenization treatment is 30 to 100 MPa, preferably 40 to 100 MPa, more preferably 50 to 100 MPa, and particularly preferably 60 to 100 MPa. When the pressure is less than 30 MPa, a precipitate may be generated during storage of the liquid fermented milk. When the pressure exceeds 100 MPa, it is necessary to use a high-performance apparatus as a pressurizing means for the homogenization treatment, which is uneconomical. From the economical viewpoint, the upper limit of the pressure is preferably 90 MPa, more preferably 80 MPa.
The temperature during the homogenization treatment is preferably 5 to 50 ° C, more preferably 5 to 45 ° C. If the temperature is less than 5 ° C., the degree of temperature decrease from the fermentation temperature is large, so the load on the operation of the cooling device increases, which is uneconomical. If the temperature exceeds 50 ° C., the fermentation proceeds before the end of the homogenization treatment, and the pH of the liquid fermented milk may be significantly lower than the pH of the curd. I need.
By the homogenization treatment, liquid fermented milk that is the final product is obtained.

The physical properties (value under storage at a predetermined storage temperature such as 10 ° C.) of the liquid fermented milk obtained by the homogenization treatment are as follows. The following values are preferably satisfied at least at the time of preparation of the liquid fermented milk (when the liquid temperature of the liquid fermented milk is adjusted to the storage temperature (for example, 10 ° C.) after completion of the homogenization treatment) More preferably, it is satisfied when the fermented milk is prepared and within a predetermined storage period.
The pH of the liquid fermented milk is 5.0 to 6.0, preferably 5.2 to 6.0, more preferably 5.3 to 5.9, and particularly preferably 5.4 to 5.9. If the pH is less than 5.0, the sourness becomes strong, the viscosity increases, and a precipitate may be produced during storage of the liquid fermented milk. When this pH exceeds 6.0, the flavor as liquid fermented milk will be inferior.
The viscosity of the liquid fermented milk is preferably 10 mPa · s or less, more preferably 7.5 mPa · s or less, and even more preferably 5 mPa · s or less, from the viewpoint of giving a good throat without a pasty feeling.
The viscosity of liquid fermented milk can be measured using a B-type viscometer. .

The acidity of the liquid fermented milk is preferably 1.0% or less, more preferably 0.8% or less, still more preferably 0.75% or less, and particularly preferably 0.8% from the viewpoint of giving a mild flavor with a weak acidity. 5% or less. The lower limit of the acidity is not particularly limited, but is usually 0.2%.
The acidity of liquid fermented milk is represented by the weight percentage which converted the acid in liquid fermented milk into lactic acid. The acidity is, for example, that after diluting 9 g of a sample with water twice, adding a phenolphthalein indicator, and then performing neutralization titration with a 0.1N sodium hydroxide solution, and the red color does not disappear for 30 seconds. Can be obtained by calculating the amount of lactic acid in 100 g of the sample from the titration amount at the end point, and indicating the obtained value in%.
The particle size of the component (casein micelle) in the liquid fermented milk is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1.5 μm or less, from the viewpoint of suppressing the formation of precipitate during storage of the liquid fermented milk. Particularly preferably, it is 1.0 μm or less.
The particle diameter means a 50% weight cumulative particle diameter (average particle diameter). The particle size is obtained, for example, by measuring the particle size distribution of components in the liquid fermented milk using a laser diffraction particle size distribution measuring device (for example, “SALD-2100” manufactured by Shimadzu Corporation). Can do.

The liquid fermented milk of the present invention is, for example, filled in a food container, stored in the form of a final product such as drink yogurt, refrigerated at a predetermined storage temperature (for example, 10 ° C. or lower), and then used for drinking.
The degree of decrease in pH of the liquid fermented milk when the liquid fermented milk is stored for a predetermined period at a predetermined storage temperature (for example, 10 ° C.) from the time of preparation suppresses the formation of precipitates during storage of the liquid fermented milk. In addition, from the viewpoint of suppressing an increase in acidity and maintaining a mild flavor, it is 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less, and particularly preferably 0.2 or less.
The liquid fermented milk of the present invention preferably does not contain a thickening stabilizer such as pectin or carboxymethylcellulose (CMC) from the viewpoint of not giving a pasty feeling. In addition, since pectin cannot exhibit the inhibitory effect of the production | generation of the precipitate in liquid fermented milk, unless it is pH 3.5-4.4 lower than pH 4.6 which is the isoelectric point of milk protein, The utility value is low within the range of 5.0 to 6.0 which is the pH of the liquid fermented milk of the present invention. In addition, since carboxymethyl cellulose is also preferably used within the range of pH 4.2 to 4.8, the utility value is within the range of 5.0 to 6.0 which is the pH of the liquid fermented milk of the present invention. Is low.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. In the following examples and comparative examples, “%” and “parts” are based on weight unless otherwise specified.
[Example 1]
By mixing 2496 g of milk, 210 g of skim milk powder, and 96 g of glucose fructose liquid sugar, the non-fat milk solid content 8.4%, milk fat content 2.0%, glucose fructose liquid sugar 2.0% and water ( After obtaining reduced milk containing the balance (87.6%), this reduced milk was sterilized to prepare a raw material for fermented milk.
Next, 100 parts of the prepared fermented milk material was inoculated with Lactobacillus bulgaricus and Streptococcus thermophilus isolated from “Meiji Bulgaria Yogurt” (trade name: manufactured by Meiji Dairies Co., Ltd.) as a starter, and a liquid at 43 ° C. While maintaining the temperature, fermentation was performed for 2 hours to obtain a card obtained by fermenting the raw material of the fermented milk. The pH of this card was 5.62.
Then, the obtained card | curd was cooled to 10 degreeC.

Next, the cooled card was homogenized under a pressure of 60 MPa using a homogenizer (manufactured by Sanwa Machinery Co., Ltd.) while maintaining a temperature of 10 ° C. to obtain liquid fermented milk. The pH of the obtained liquid fermented milk was 5.62.
Next, this liquid fermented milk is stored while maintaining a liquid temperature of 10 ° C., and pH, acidity, viscosity, particle size at each time point from the start of storage to 1 day, 4 days, 8 days, and 11 days after the start of the storage. Each physical property was measured, and the presence or absence of precipitates and the state of liquid fermented milk were examined visually. The results are shown in Table 1.
In addition, as above-mentioned, acidity was computed by the method of performing neutralization titration with a sodium hydroxide solution, after adding a phenolphthalein indicator. The viscosity was measured using a B-type viscometer. The particle size was obtained based on the particle size distribution obtained using a laser diffraction particle size distribution measuring device (product “SALD-2100” manufactured by Shimadzu Corporation).

  In Table 1, the effect of the present invention was seen until “storage at 10 ° C. for 8 days” where the pH of the liquid fermented milk was 4.95, but “storage at 10 ° C. for 11 days”. After that, the viscosity and particle diameter increased, and the state of the liquid fermented milk became solid due to the aggregation of the milk, and the effect of the present invention was not seen. Therefore, it was found that the effect of the present invention can be seen if the pressure of the homogenization treatment is set to 60 MPa and the pH during refrigerated storage of the liquid fermented milk is 5.0 or more.

[Example 2]
The experiment was performed in the same manner as in Example 1 except that the pressure of the homogenization treatment was changed from 60 MPa to 30 MPa. As a result, the pH of the curd was 5.62, and the pH of the liquid fermented milk was 5.62. Moreover, the liquid fermented milk cooled like Example 1 is preserve | saved keeping the liquid temperature of 10 degreeC, pH, acidity, in each time of 1 day, 3 days, and 6 days after the storage start time, The physical properties of viscosity and particle diameter were measured, and the presence of precipitates and the state of liquid fermented milk were examined visually. The results are shown in Table 2.

  In Table 2, the effect of the present invention was observed until “storage at 10 ° C. for 3 days” where the pH of the liquid fermented milk was 5.0 or more, but the pH was 4.80 “storage at 10 ° C. for 6 days. After that, the viscosity and particle diameter increased, and the state of the liquid fermented milk became solid due to the aggregation of the milk, and the effect of the present invention was not seen. Therefore, it was found that the effect of the present invention can be seen if the pressure of the homogenization treatment is set to 30 MPa and the pH during refrigerated storage of the liquid fermented milk is 5.0 or more.

[Comparative Example 1]
The experiment was performed in the same manner as in Example 1 except that the pressure of the homogenization treatment was changed from 60 MPa to 0 MPa. Moreover, the liquid fermented milk cooled like Example 1 is preserve | saved keeping the liquid temperature of 10 degreeC, pH, acidity, in each time of 1 day, 4 days, and 5 days after the preservation | save start time, The physical properties of viscosity and particle diameter were measured, and the presence of precipitates and the state of liquid fermented milk were examined visually. The results are shown in Table 3.

In Table 3, even when the pH of the liquid fermented milk is 4.94 and “stored at 10 ° C. for 4 days”, the viscosity and the particle diameter increase, and the liquid fermented milk becomes a paste-like shape that is solidifying at the bottom, resulting in precipitation. The effect of the present invention was not observed. In Example 1 where the pressure of the homogenization treatment was 60 MPa, the effect of the present invention was observed even in liquid fermented milk having a pH of 4.95. In Comparative Example 1 where the pressure of the homogenization treatment was 0 MPa, the effect of the present invention was observed. Was not seen. From the time of “storage at 10 ° C. for 5 days” at pH 4.76, the viscosity and particle size increased, and the state of the liquid fermented milk became solid due to aggregation of the milk, and the effect of the present invention was not seen.
Therefore, in order to obtain the effect of the present invention, it is necessary to homogenize the fermented milk at a pressure of 30 MPa or higher when homogenizing (liquefaction) the fermented milk to obtain liquid fermented milk having a pH of 5.0 or higher. It was demonstrated in Example 1, Example 2 and Comparative Example 1. If a lactic acid bacterium having a long period until reaching pH 5.0 during refrigerated storage is used, the storage period can be extended.

Claims (4)

(A) a card preparation step of adding a lactic acid bacterium to a raw material of fermented milk that does not contain a thickening stabilizer and fermenting to prepare a curd of pH 5.4 to 6.0;
(B) A homogenization treatment step of performing a homogenization treatment of the card under a pressure of 50 to 100 MPa to obtain a liquid fermented milk having a pH of 5.4 to 6.0 and containing no thickening stabilizer,
A method for producing liquid fermented milk comprising Method for producing a liquid fermented milk according to claim 1, step homogenization process (B) is performed at a temperature of 5 to 50 ° C.. The method for producing liquid fermented milk according to claim 1 or 2 , wherein the liquid fermented milk has a viscosity of 10 mPa · s or less. The method for producing liquid fermented milk according to any one of claims 1 to 3 , wherein the acidity of the liquid fermented milk is 0.5% or less.